The present invention relates to a window or door construction and more particularly to a window or door frame which may be utilized to mount a window or door pane of either a rigid or semi-rigid self-supporting material or a flexible plastic membrane in parallel spaced relation to an existing window glass or door panel to provide an insulating layer of air between the glass or panel and the pane.
Insulating windows and doors of various designs are widely used to conserve energy by preventing the escape of heat through windows and doors of residences and businesses. Because the use of such windows is seasonal, it is desirable for panes used in such insulating windows and doors to be inexpensive and to be easily installed and removed. It is also desirable that they not substantially detract from the appearance of the building on which they are used.
Various storm window and door constructions have been used in the past. In such constructions a pane is attached to a window or door frame in parallel spaced relation to the pane of window glass or door to provide a layer of dead air between the glass or door and the pane for insulating against cold or heat.
Where flexible plastic membrane type panes are used, these are commonly secured to the outside of a window frame by wooden strips nailed into the window frame. These have proved unsatisfactory because the wood strip is usually made of poor quality lath which often splinters or splits when nailed in place. Such wood strips are also unsightly and detract from the appearance of the building. More recently plastic membrane type panes have been mounted in window frames by rigid framing strips of the type disclosed in my prior U.S. Pat. No. 3,991,806 and the references cited therein. These prior art framing strips, while a substantial improvement over wooden lath, are only suitable for the installation of flexible plastic membranes and cannot be used to install rigid panes. The latter are easier to handle and install, and are stronger than flexible plastic membranes.
Another prior construction includes framing strips permanently secured in window frames or in storm doors to mount rigid or semi-rigid panes. For support, such rigid panes typically are mounted in a metal sash or frame which mates with the door or window framing strips. The necessity of such a sash adds to the weight and expense of the construction and makes it impossible to utilize the framing strips for mounting panes or screening not having a compatible sash. In the case of storm doors, a sash-mounted pane or screen is typically held in place by metal clips attached by screws to the storm door. The sash-mounted storm door panes and screening are typically interchangeable so that the door may be used alternatively as a storm door during cold weather and as a screen door during warmer weather. This door construction is relatively expensive as compared to the present invention; and the installation of such sash-mounted panes and screens is time consuming and requires the use of tools.
Attachment means which serve equally well for securing the edges of either an unframed rigid pane or an unframed flexible plastic membrane are heretofore unknown.